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It’s a Wiggly, Wiggly Universe

Image of cosmic microwave background

Figure 1. The Cosmic Microwave Background as revealed by NASA’s WMAP satellite. This is a picture of the whole sky in microwaves, and shows the fluctuations of matter in the Universe only 400,000 years after the Big Bang. The sky is covered in little hot and cold spots of size ~1°, corresponding to the distance sound can travel in the early Universe. Image: NASA / WMAP Science Team

By Karl Glazebrook

A map of the universe as it existed six billion years ago is close to completion, and may provide new insights into the physics of dark energy.

The full text of this article can be purchased from Informit.

In the Beginning there was Light. But there was also Sound and Fury...

13.7 billion years ago our universe began in the Big Bang, when the whole of infinity was compressed to a singular point. While we do not yet understand the moment of singularity, cosmologists such as Stephen Hawking see that as their ultimate quest.

But putting aside the first 10–32 seconds or so we think we understand the Big Bang pretty well. After all it was simple, almost entirely uniform and devoid of any structure except for tiny fluctuations. The physics of such a medium as it expands and cools can be described almost exactly.

It is from these fluctuations that the giant galaxies we see today grew, and we know our physical model of them is very accurate as we can observe them in fine detail in the Cosmic Microwave Background (Fig. 1). Although our map of the Cosmic Microwave Background looks random, it turns out that the magnitude of the random fluctuations is different on different scales. For example, 1° scales show much bigger fluctuations than larger or smaller scales. What causes these patterns?

The answer lies in the physics of sound, for the universe was not always a vacuum through which sound cannot propagate. For the first few hundred thousand years after the Big Bang it was very thick and dense, and acoustic waves in the density of matter would propagate...

The full text of this article can be purchased from Informit.

Karl Glazebrook is Professor of Astrophysics at Swinburne University, and a founding member and joint-leader of the WiggleZ survey (wigglez.swin.edu.au).